The small pterosaur[n1] Rhamphorhynchus is known from a large host of specimens from the Late Jurassic of central to western Europe, mostly Germany and surrounding countries. It is known from complete specimens, to well-preserved partial, to utter crap. It is known from squished, 2D preserved specimens, and from 3D preserved fully prepared ones. Once, it was known from a large host of species, but numerous studies in the the mid-1990s indicate that most of these are probably a single species, merely ontogenetically different. There’s some quibbling that can be had about the ontogeny, as the jaw in Rhamphorhynchus spp. varies considerably, but we’ll get around to that some time later.

Rhamphorhynchus represents a small challenge to reconstruction given the enmeshing of its teeth: long, curving teeth splay anterior and lateral to the jaw, fewer on the mandible than the upper jaw, with prow-like edentulous tips. The jaw tips are toothless, but some specimens show evidence of soft-tissue projecting from them, best described by Wellnhofer (1975), who noted that in “gemmingi“-type specimens the straight prows bore straight or slightly upturned beak like shapes showing banding:

Figure 5 of Wellnhofer (1975) with caption (in the original German) included.

“Intermedius“- and “longicaudus“-type specimens, however, have mandibles with pronounced curves, and the shape of the soft-tissue seems to reflect this, while the premaxilla of the “intermedius“-type shown above also bears a hook (this one downward-oriented) but the underlying bony beak does not suggest such a structure is present.

There is banding in this tissue, which suggests there are layering issues involved: the structure so perceived is either split such that we are perceiving the interior, banded segments of tissue or that, rather, the material represented is not all of one material, but comprises a series of soft or hard tissues other than bone, such as cartilage, or even more pliable soft-tissues associated with the dermis. Tissue analysis through a variety of non-invasive (or even invasive, sorry guys!) techniques would have to be performed to differentiate if the banding did represent distinct tissue types, growth, etc. I’ve chosen to take the road most traveled and interpret the structures as being keratin, but I will warn you that, even interpreted as rhamphotheca, the extreme thickness and protuberance of the structures from the jaw tips may belie their use as a semi-hard, rhamphothecal tissue; that there isn’t a lot of data on the structure of the jaws at the tips of rhamphorhynchids to answer the question of what, and how much, of a rhamphotheca might be present. So I tend to be inclined to present the reconstruction I’d offer without keratin at all, but it does help with the reconstruction that is now part of my banner. The issue, of course, is that when the jaws closed, the tips of these structures may very well have touched, or even crossed, and that would certainly be true in the “intermedius“-type seen above though the “gemmingi“-type would likely not.

Note that even were the tip of the upper “rhamphotheca” shown here turned upwards, the tips might still touch.

It’s been noted that Rhamphorhynchus, like many Solnhofen pterosaurs, was piscivorous, but it is hard to reconcile this with incidental recovery: All of the Eocene birds from the Green River Formation, birds collected from the Jiufotang and Yixian Formations, etc., are collected from lacustrine, marine, or estuarine environment, and for pterosaurs from the Jiufotang, Yixian, Solnhofen, and especially Santana and Crato Formations, virtually the entire fauna is known from what are certainly collected remains recovered from an anoxic (oxygen-deprived) low-energy body of water, which is conducive to preserving body fossils of small animals. Not all of these species recovered were aquatic or aerial, indicating that this preservational regime would tend to collect animals that gathered or were transported to the deposit regardless of where they might otherwise inhabit. And what this means is that it is not necessarily true that all such animals are piscivorous. But I will eventually get around to discussing this topic when I can cover it in greater depth; needless to say, the topic suggests at least a perspective that differs with Rhamphorhynchus (any species, if polyspecific) being piscivorous.

Taxonomic note:Rhamphorhynchus muensteri was originally named by Georg August Goldfuß (Goldfuss) in 1831 as Ornithocephalus muensteri. Hermann von Meyer in 1846 coined the name Rhamphorhynchus and moved muensteri into it. This had been the “law of the land” (followed by most workers, including Wellnhofer, 1975) until Bennett (1995) provided ample data that suggested all Rhamphorhynchus species were ontogenetic morphs (or “semaphoront,” not his term [edited: the quoted term was originally “biont,” but the term “semaphoront”[n2] was meant instead, and is now used]), and thus would all become muensteri.

[n1] Relatively speaking. Rhamphorhynchus was about the same size as contemporaneous Pterodactylus, with a wingspan as an adult exceeding 1m.
[n2] Hennig’s use of the term (1966) denotes, as in insects, particular (and distinct) phases in the life cycle of an organism. It has been adapted for use by some biologists to reference “classes,” as in ceratopsians, hadrosaurs, Bennett’s year-classes of Rhamphorhynchus (1995) and Pterodactylus (1996). I find the term ugly, but it has some usefulness.

24 Responses to A Skull For Rhamphorhynchus

If I’ve read your last paragraph – sorry, but I find some of it a little hard to follow – then you’re saying Rhamphorhynchus is an unlikely piscivore and probably an inland species? If so – and again, sorry if I have the wrong end of the stick – there’s multiple lines of evidence to refute this. At least two specimens of Rhamphorhynchus have fish gut content (a third was proposed, but it was bogus: the ‘fish’ turned out to be misaligned sternal ribs), and it’s recently been found to have eaten cephalopods. It’s abundance in Solnhofen is way higher than any other pterosaur by something like a factor of 2 or 3: there are hundreds of specimens of it, compared to say, 2 for Anurognathus, 3 for Scaphognathus, meagre handfuls for the exotic pterodactyloids and a few dozen Pterodactylus. One the functional side of things, in addition to the obvious ‘fish grab’ jaws, you’ve got multiple flight studies which find wing shapes suited to gull-like marine-soaring – it’s one of the few pterosaurs that most- maybe all – flight studies seem to agree about! The proposed lifestyle of Rhamphorhynchus as a seabird-like animal is well supported from functional, taphonomic and direct palaeoecological evidence, providing a lifestyle inference which is probably more robust than that of any other pterosaur.

The argument is unfinished. It isn’t intended to be complete in this post. I needed some more time to approach the argument of what an animal like Rhamphorhynchus could do with its jaws, since the premise as a surface skimmer or other style of fish-catcher can be considered untenable. As for the “obvious” “fishgrab” jaws, there is that, but the argument about habitus should be divorced from its diet. Not all Solnhofen animals dwelt in the area of their deposition; you of all people should be aware of this!

I’m actually curious what “fishgrab” should jaws look like to you, Mark?

The main problem with food acquisition in pterosaurs has been that virtually all have been assumed to be piscivores first, and screw any other option. This applies to Rhamphorhynchus as much as it does Pterodactylus, however distinct their jaws. Or the “obvious” “fishgrab” jaws of ctenochasmatids. Or the “obvious” “fishgrab” jaws of any other Solnhofen pterosaur. I’d like to think biomechanical function of the jaw, muscle orientation and size, would have better things to teach us about diet than mere association, no matter how numerous the specimens.

Of course I’m aware of that, and there’s no need to be patronising. I can only assume you’ve not really considered the Rhamphorhynchus fossil record against that of Solnhofen animals: Rhamphorhynchus is probably the most abundant non-pelagic vertebrate in Solnhofen, represented by something like 130 specimens in museums (who knows how many privately). It’s regularly preserved as complete, articulated skeletons, many of which preserved soft-tissues in exquisite detail: claw sheaths, mummified bodies, wing membranes of all kinds etc. Clearly, minimal amounts of decay set into most Rhamphorhynchus specimens before they reach their site of fossilisation: physical weathering, transportation and biological breakdown did not affect most Rhamphorhynchus carcasses very much. Moreover, it has an almost complete growth series (just missing eggs) where growth stages are represented by multiple individuals, and several specimens which show direct evidence of lifestlye and palaeobiology (see below). This contracts with the preservational state of almost all other Solnhofen pterosaurs, which are relatively rare, lack good soft-tissue remains and growth series, and generally lack complete and articulated skeletons (Pterodactylus, of course, is an exception here). The near perfect preservation of most Rhamphorhynchus specimens, their abundance and excellent ontogenetic representation indicates that populations of this creature lived in the immediate vicinity of the Solnhofen lagoon, routinely dying around, immediately above or within the lagoon itself – they must have had an express ticket to the calm, decay-resistant bottom waters of Solnhofen or their fossil record would be nowhere near as good. Inferring that Rhamphorhynchus were routinely washed into the lagoon from further afield requires you to explain why they’re routinely found as near-perfect fossils, which we don’t have to do if we assume they lived nearby.

On being a ‘marine’ pterosaur: The fact that other pterosaurs do not have preserved gut contents (mentioned below somewhere) is a moot point: you can’t argue using negative evidence. With at least three specimens incontrovertibly demonstrating Rhamphorhynchus dined on pelagic marine organisms, it is clearly parsimonious to assume they took prey of this kind on occasion, perhaps often (law of averages). The fact that we have five specimens of Rhamphorhynchus wrapped up with the predatory fish Aspidorhynchus, as well as Rhamphorhynchus bones preserved in gut regurgitate from another (probably fish) marine predator is further indication that they often interacted with creatures in the marine realm. You might argue that “…biomechanical function of the jaw, muscle orientation and size, would have better things to teach us about diet than mere association, no matter how numerous the specimens”, but any palaeoecology textbook will disagree with you. Direct evidence tells us what actually happened, whereas models we make are only as good as the assumptions we include. Biomechanics and functional morphology actually provide the lowest level of certainty about the lifestyle of a fossil animal, whereas direct evidence provides the most reliable – that’s how it is. This is not to play down the importance of the former of course, but you can’t trump actual evidence with a theoretical inference.

How Rhamphorynchus caught their prey, as discussed in my book (along with most of the other points here, in fact), remains largely uninvestigated, but the large, procumbent, well-spaced spear-like teeth (the ‘fish grab’ routinely mentioned in pterosaur literature – see Osi’s 2010 analysis of early pterosaur teeth, Unwin 2005, Wellnhofer’s many papers and books on Rhamphorhynchus etc. The only other animals mentioned with obvious fish grabs are ornithocheirids: your suggestion that ctenochasmatoids etc. have ‘obvious’ fish grabs is a Headden original), streamlined jaws, orbit reduced to jawline level and – possibly – enlarged anterior cervical vertebrae may indicate prey was taken by dip feeding. I also don’t have a problem with these chaps swimming to find prey. Even the ‘no swimming please’ paper by Hone and Henderson published this year concedes that Rhamphorhynchus had a stable floating posture. Again,the wing ecomorphology of Rhamphorhynchus is indicative of soaring flight in open environments: it has unusually long, narrow wings compared to nearly all other non-pterodactyloids, whereas more likely terrestrial species (i.e. scaphognathines, wukongopterids) have much shorter, broader wings. Weakly developed hindlimbs, appendages and a shoulder girdle which limits forelimb adduction indicate that Rhamporhynchus was poorly adapted for terrestrial locomotion compared to other pterosaurs, even non-pterodactyloids. There’s still a lot of work to be done here, but the provisional studies done in this area all fit the marine, fish/squid eating model.

And yes, there is a problem with piscivory being the de facto interpretation of pterosaur lifestyles (I may have said this more than anyone) but – as documented in literature I know you’re familiar with – there is a lot of evidence to suggest a generally piscivorous lifestyle is accurate for Rhamphorhynchus. I’m not, of course, arguing that these animals _only_ ate pelagic marine animals – few species are so restricted in their diets – but as a general rule, considering Rhamphorhynchus a marine, gull- or tern-like pterosaur which lived on the shores of Solnhofen islands is a robust hypothesis supported by multiple lines of evidence. This is why I picked you up on your ‘unfinished’ argument: it seems like a bit of a non-starter, akin to saying “Tyrannosaurus is always assumed to eat meat, but…” I wait to be proved wrong on this, but I think the weight of evidence is against you.

I find it curious that you chastise me for being patronizing, but the entirety of your post takes that posture. I do not dismiss your knowledge on this; indeed, I made a point of deferring to it on the nature of arguments about fossil accumulation as opposed to assumptions of “lived where it died.” You’d be surprised how much people with appreciable amounts of education still make this argument.

But you seem to be missing something in your piece on the nature of Rhampohorhynchus. Specifically, that I did not state that Rhampohorhynchus was not, in fact, piscivorous, a point I had to reiterate in my replies above. I shouldn’t even need to defend this, as even had I said that, the burden of the argument would rest on me: You’d merely need to claim that I haven’t proven my case and sit back. Instead, you write a tremendous amount lecturing me on the reasons why Rhampohorhynchus is what I seemingly said it isn’t. So let me be clear:

1) I did not say Rhampohorhynchus isn’t piscivorous.
2) I do call into question the allusion that it is adapted to a fish-acquiring habitus.
3) I made a hand-wave at looking at biomechanical data regarding its jaw function; as so far, the only biomech work done on Rhampho has been to look at its wings and potential launch capability, of which I have nothing to say.
4) I passed an allusion of the shape and arrangement of teeth about the function of the “fishgrab” jaws; but so far, the only biomech study on the heads and functional anatomy of these “fishgrab” apparatuses has been an unpublished thesis (Fastnacht), and this requires resolution; nor is the data necessarily “out there” to be drawn upon.
5) I passed the distinct cranial morphologies of the basal ctenochasmatoid Pterodactylus by the “more primitive” Rhampohorhynchus by each other and note how both are generally assumed to be piscivores with marine and near-shore adapted lifestyles; how resolving the distinction between these (and, indeed, with more derived ctenochasmatids) is required.
6) In short, I would argue for a “full data” perspective, rather than trying to draw on smaller bits and ignoring the needful biomech to help with work.

I did ask for what you felt influenced the need to have Rhampohorhynchus as a piscivore, and your third paragraph sums this up nicely, but didn’t need to sum up what you recognize (I hope) what I already know about the literature on these taxa. There are gaps in everyone’s knowledge, especially — I cannot emphasize this enough, especially — mine.

It seems you think I’m lambasting you here – I’m not meaning to, and apologies if that’s how it comes across. I’m simply responding to your comments in your last paragraph, which – to me – imply that Rhamphorhynchus is not the piscivore or marine animal it’s often said to be. This sentence is particularly suggestive:

“I will eventually get around to discussing this topic when I can cover it in greater depth; needless to say, the topic suggests at least a perspective that differs with Rhamphorhynchus (any species, if polyspecific) being piscivorous.”

As said in my first comment, I may have read this wrong, but I take from this that you’re saying “there are reasons to think Rhamphorhynchus isn’t a piscivore”. So to my eyes, you did kinda say that it isn’t – or at least, the idea is not as tight as we all think it is. Hence my response, because I found that rather surprising given the well-known evidence we have from taphonomy, fossil associations, basic funky morph etc. I did assume you knew about this stuff – again, more surprise – but I went into more detail because your first response only echoed points made in the article about allochthonous associations and all, which seemed odd given the record we have for Rhamphorhynchus. Apologies if it came off as a lecture: it was merely meant to explain my position on this topic in a discussion where I felt it needed clarity.

I actually want my arguments lambasted. That is why I posted this to my Twitter and invited people to come and watch. Not for defense, but to entice discussion. I would rather my arguments come under the full heat of scrutiny. But I made a very casual reference about an argument I was thinking of for future presentation (the question of diet in Rhampho) and it is my intention to flesh this argument out. But I’ve not made that argument yet; it seems that many are assuming I wish to throw piscivory to the wind here. I will certainly be contrasting the various jaw morphologies amongst the Solnhofen pterosaurs, the variety of of which is very high (which you are certainly aware of). The idea is certainly not as tight as it should be, and the reason for this has been to ignore use of biomechanics of the head itself to suggest possible apprehension methods. Wings are one thing, but the variety of dietary styles employed by birds with gull-like wings is greater than they’re given credit for.

And honestly, if you feel you need to lecture me … I have thicker skin than some!

There’s also the fact that many modern “piscivorous” birds like seagulls are more accurately described as omnivores that feed regularly on terrestrial prey and carrion as well (hell, early Neornithes might have descended from such a bird that eventually resumed tofull terrestriality).

Rhamphorhynchine rhamphorhynchids were piscivores, true, but whereas they were dedicated piscivores like modern pelagic birds or opportunists like coastoal birds is less clear. We have evidence of the taking of piscivorous prey, but given the predominance of rhamphorhynchines over all other types of non-monofenestratan pterosaurs in the terminal Jurassic, occuring in a variety of environs from far inland to deep sea settings, I think seagull comparisions ring more true than petrel comparisions.

I bow to the experts on predictions of lifestyle to wingshape dynamics, but won’t begrudge the seagulls that I grew up with living in far-far-inland Idaho from making a living so far from the sea. I give them, being generalists that are nonetheless primarily adventurers of the sea, their due. That said, there are other issues when it comes to Rhamphorhynchus than merely wing shape, and it was this that I was going to get into when it came to concerns over plugging diet as though habitat were the main determinant. I am further reminded that diet is well-known for several specimens of Microraptor zhaoianus, and it was lauded as a piscivore in at least two papers, but the data is based on limited information: even with a dozen specimens, three specimens with fish in their guts doesn’t mean Microraptor is a piscivore.

To be fair, given wing shape limitations on pterosaurs (they could not dystally broaden their wings, for instance), I think all we can say for certain about rhamphorhynchines is that they were specialised soarers (and seagulls, with their seabird wings, can fly very well in inland settings).

I am reminded of Microraptor and Confuciusornis indeed, though I suppose the higher number of Rhamphorhynchus associated with fish remains and the now recent cephalopod stomachal finds make an argument for dedicated piscivory more reasonable than for those paravians.

All this about seagulls aside, bear in mind that I am not arguing against piscivory. I do note however that not so many Rhamphorhynchus specimens are associated with clear remains of last diets; like many pterosaurs remains, there are many which show none at all. I am discussing, for the moment, the degree to which we may infer piscivory, and by what means.

The specimen is primarily derived from WDC CSG 255, described by Frey & Tischlinger (2012). However, the specimen is also modified from additional specimens elucidating details of associations of bones in various views so as to make sure the elements are consistent. As not all specimens are perfect, and I am not weighing in on the “which specimens are species” issue (as I am generally following Bennett until further notice), the specimen is mostly an “idealized” individual, and very schematic, rather than based on ONE thing.

Hennig proposed the term “semaphorant” for “an organism at a particular stage of life” (like at a particular instar of an arthropod). David Evans et al. have brought back this term in SVP (in lieu of the MOR’s neologism “ontogimorph”.

It seems to me, as a non-pterosaur worker, that Mark has the paleoecological ducks all in a row (and everyone seemingly agrees with this). It seems like the question is the degree of piscivory. Jamie you discussed Rhamphorhynchus as perhaps being more of a generalist in the comments (though not in the post itself – correct me if I am wrong) than others who view it as an obligate or near-obligate piscivore and are suggesting biomechanics can provide evidence for or against this hypothesis. I just want to make sure I have things straight because…
…it seems like the dentition and beak tips of Rhamphorhynchus are highly specialized for something. Those teeth and odd tips are not a good match for known generalists in the fossil or modern animal record. It is energetically expensive to grow all that tissue and there are some things that would be inhibited by those procumbent teeth (carrion feeding comes to mind). That means that the amount of energy available to this animal has been reduced in favor of energetically expensive structures. If these structures are not better at acquiring energy/nutrients than a generic pterosaur beak/tooth set then there is no selective pressure towards them – especially if they reduce food sources available to the species. The teeth and odd rostrum must be better at acquiring energy than the loss in energy they require to grow instead of an edentulous jaw. We know R. spp. ate fish through direct evidence (as Mark points out). We know that human designs similar to Rhamphorhynchus’ jaws are well adapted to catching fish (http://i167.photobucket.com/albums/u148/Tim_Rast/PortauChoixreproductions052.jpg). This strongly suggests that Rhamphorhynchus was a specialized piscivore. I know some of this is a rehash of what others have said but I felt like the energetic/selective pressure angles had not been covered previously.

An additional supporting point to Rob’s point here: Rhamphorhynchus’ jaws are very derived even with Rhamphorhynchinae (or, if you don’t buy that clade, derived compared to all close relatives). Indeed, much of its anatomy is rather specialised (the longest wings, the most ‘hatchet shaped’ humerus), representing the development of the most ‘extreme’ rhamphorhynchine bauplan known. Dietary and habitat specialisation may account for some of this anatomy.

I’d rather leave my discussion on several of these points, as I have some fairly specific arguments to make about them that even have evidence to back them up (and I don’t need some special information only I can see to do so). However, as I noted upstream and in the post itself, my argument is unfinished and the comment at the end of the post was more of a throwaway line that has, nonetheless, enticed healthy discussion here. Trust me, I’ll let you lambaste me further when I get around to discussing the issue.

But when it comes to biomechanical arguments, let me state up front that the work done to suggest the function of the jaw in anything similar to a fish-acquiring apparatus has not been done. Not by anyone. People, especially Wellnhofer and all others down through the years, have made the basic premise that the jaws are adapted for catching, piercing or restraining fish, but none of them have made the necessary arguments to explain mechanism. This, I think, would have to come first.

I think that in a case where an animal is known to do something (in this case ingest fish, as per the fossil record) the mechanical explanation is secondary, not primary. It is of interest how these organisms acquired these prey items and may help elucidate other feeding strategies but no matter what the mechanical models say we can state they ate fish. You said, “none of them have made the necessary arguments to explain mechanism. This, I think, would have to come first.” I think this is putting the cart before the horse. We don’t have to explain the mechanism by which humans walk upright in order to know that healthy adult humans are bipeds. Is it good to know the biomechanics of how this happens? Yes. But we don’t need to know the mechanism in order to state that an action occurred.
Another example: How did theropod dinosaurs turn while walking? We know that they didn’t plod in straight lines their whole lives and die when they met an obstacle. Folks had proposed a model of rotation of the leg at the acetabulum. This model was challenged at SVP in 2012 where motion X-Rays show substantial rotation at the knee joint in chickens. Yet in either case it is an attempt to describe what we know already happened. It doesn’t matter which model is right if we want to say, “theropods could turn while walking.” That is a fact.
I understand exactly where you are coming from with testing long held assumptions about animals (Coelophysis cannibalism in my case). But in this case the taphonomy seems to show ingestion and the taxonomy isn’t an issue (not discussing cannibalism). If the pterosaur has a fish in the chest cavity that shows signs of digestion then that pterosaur was piscivorous. Biomechanical hypotheses can’t overturn observed data.
Anyway, I will save further comments until the next installment of your blog, since you say you have more to come. I look forward to it!

There is no case that is unassailable. Now, I’m not going to get all pseudoscience-y and try to claim I have found a better way. My argument says that biomechanics should be as prominent as as paleoecology when it comes to inferring diet; the existence of one form of this data doesn’t necessarily rule out the value of the other. What do you think would happen if the two conflicted in conclusion? How do I rate paleoecological data, even if comprehensive, when biomech data implies aspects of that data were just wrong? Say, the jaw of an animal couldn’t withstand the hard-crushing diet that eating nuts (say) would require, yet is found amongst nut-producing plants? With Microraptor, the claim was to find morphological data that would somehow support a piscivorous diet, being the slight inclination of a mesial dentary tooth, whilst the gastric remains show inconsistent preservation of such a foodstuff? Avian, mammal, and fish remains, implying tree, understory, and waterside localities, but still you’d want to make it more favorable to one diet than others.

Are any of you guys experts? Because I recently saw one the other night. I live in coastal city. It was a foggy night driving by a body of water, and assuming it was a pelican flying by. I noticed something very odd and appeared to have a dragons tail, which pelicans don’t have.

CC-BY is the fair use clause. It takes almost no effort to find and note the name of the author of the illustration, especially in a field as SMALL as paleontology. Much effort goes to researching these papers at times; more effort can go into establishing that the illustrations are properly sourced. Other journals do this, but the tabloids sadly have had issues with this. This is not the first time this has happened with respect to the silhouettes, either. Even to think that using the fair use doctrine as an escape clause to avoid citing the author of one’s illustrations is to justify larceny. I am not making that claim here; I just think it’s a little lazy, and the publishing process makes no effort to enforce this. CC-BY may not be enforceable in the respect of most laws, as in it’s not an actual copyright protection provided for free (since I lack the income to copyright with enforceable punishment of infringement).